If you were in control of your own email system, you could install a bayesian spam filter such as DSPAM. This is about as good as it gets, once trained.
Since you're not, you're pretty much left to either accepting whatever spam measures NTL and hotmail give. Your NTL is probably a POP account? If so you could check it with Thunderbird for example (
http://www.mozilla.com/thunderbird), which has a pretty decent spam filter once you've trained it for a while. That way your spam will at least end up in a special purpose spam folder, and not with the good email.
If you know someone on gmail (or maybe someone here will invite you?), get a gmail account. Does the same job as hotmail does, but it's far superior (including having better spam filters).